As people get busier, they want to bring their favorite drink when they are commuting. They also want to keep their beverages warmer or colder longer so they can get the best tastes. These desires have been met with a vacuum mug, or thermal mug, that insulates the beverage inside from the temperature outside, and has become a modern convenience that busy people and commuters cannot function without. The more convenient and functional vacuum mugs get, the more often and more people use them. In recent years, among other changes, vacuum mug caps are improved substantially and provide more utilities.
For example, a vacuum mug with a stopper or screw cap that has a strainer or infuser attached to the underside of the cap, and an opening for sipping has allowed a coffee or tea drinker to brew her coffee or tea on the go as if the user takes a brewing pot with her, and enjoy the brew. The vacuum mug keeps the hot water hot, so the coffee or tea in the strainer or infuser has time to brew while the user travels to the workplace. With the sipper opening separate from that of the strainer or infuser, the user does not have to wait until arriving at the office to enjoy the beverage. She can enjoy the beverage while driving without removing the strainer or infuser.
Since a vacuum mug can keep both cold and hot beverage colder or warmer, respectively, longer than without one, a user can perhaps use it for hot coffee or tea in the morning and cold soda in the afternoon. In this use scenario, however, the user needs a versatile mug that lets her sip the hot coffee or tea, and gulp cold beverage without removing the cap. Currently, no mugs on the market offered this versatility. A user can only buy a mug for sipping hot coffee or tea, and another mug for gulping cold beverage. Alternatively, she has to remove the cap for gulping cold beverage, giving up the insulation benefits of the vacuum mug, and also risking a spillage.
Therefore, it is desirable to have a spill-proof and versatile cap to increase the utility of a vacuum mug.